powering 86 LEDs with an arduino powered by the VIN pin

So, i have a strip of WS2812B individually addressable RGB LEDs. I need them to be in a sorta compact system, without any external connections. I have enough space for batteries, so room isn't a problem. I have 4 3.7V 1200mah LI-PO drone batteries that should be enough to power the system with an arduino uno, and 86 LEDs. Now, i haven't powered the arduino with VIN before, so any info that could help is definitely useful. Thanks in advance!

You need to get yourself a DC-DC boost converter. Make sure it can handle the input voltage and delivers the output current you need.

Test it before you attach your sensitive hardware and check the datasheet of the components used. Sometimes the cheap electronics promise more than they deliver.

Count the LEDs and multiply by 18 mA, this gives your total LED current. Now it gets interesting we will assume the arduino cannot comfortably handle the LED current so you are going to need a separate power supply for that, a Boost would work great. You will need another Boost converter to raise the voltage to about 7.5 volts for the VIN pin. I use a SWAG of about 70 mA for the micro, Total the currents and use a number of about 85% efficiency for the converters. You can use the same boost converter for both but the 5V becomes very critical. Use a volt meter to validate and set the boost converters.This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil

I have an alternative suggestion. Get a 3.3V 8 MHz Arduino Pro Micro Mini. Use the lipo batteries to power the strip directly and take extra wires from the lipo to power the Pro Micro Mini via its 3V3 pin, not the Vin pin. The chip on the 3.3V pro micro mini is the same chip as on many other Arduino and will be quite happy at 3.7V or the 4.2V of a fully charged lipo. The more you can avoid using boost converters and regulators, the less battery power will be wasted and the longer the battery will last between charges.

JakeMX:
Now, i haven't powered the arduino with VIN before, so any info that could help is definitely useful.

Good, here it is: Do not power the Arduino via the "Vin" pin. That is the wrong way to power it for any serious project; it wastes power and cannot provide for significantly more than the processor alone, perhaps a couple of 20 mA LEDs. Unfortunately many tutorials are woefully misleading in this respect.

The Arduino runs on 5 V. If you are not using the USB interface - as you will not be for any battery project - the voltage is not so critical; a 16 MHz device may not be reliable below 4 V. For a battery project you do not want the USB interface (it wastes power), so use an Arduino that does not have it, which is the Pro Mini, An 8 MHz Pro Mini will operate at 3.3 V or anything up to 5 V, so is the perfect fit for a LiPo battery.

JakeMX:
So, i have a strip of WS2812B individually addressable RGB LEDs. I need them to be in a sorta compact system, without any external connections. I have enough space for batteries, so room isn't a problem. I have 4 3.7V 1200mah LI-PO drone batteries that should be enough to power the system with an arduino uno, and 86 LEDs. Now, i haven't powered the arduino with VIN before, so any info that could help is definitely useful. Thanks in advance!

There are some options to do that, if you are planning to use the neopixels at full brightness then I recommend you to use two or three batteries in serial configuration to have 7.4V or 11.3V that depends on how long do you want to keep it running on baterries, then you can feed the Arduino UNO via the power jack that way you can avoid disconnections, you must remember that neopixels work at 5V then you will need to use a Step Down Converter to feed the LEDs something like the Mini 360 MP2307 (https://cdn-shop.adafruit.com/datasheets/MP2307_r1.9.pdf) and don´t forget the Adafruit´s recommendations to "place a 300 to 500 Ohm resistor between the Arduino data output pin and the input to the first NeoPixel" and "Before connecting NeoPixels to any large power source (DC “wall wart” or even a large battery), add a capacitor (1000 µF, 6.3V or higher) across the + and – terminals" (Best Practices | Adafruit NeoPixel Überguide | Adafruit Learning System).

But if you don´t want to get blinded by the Neopixels and want to look them directly you can set the brightness to a value about 60 ~ 70 out of 255 that means 25% it seems low but beleive me at that value you can watch the LEDs without any problem, in this case you can use again 2 or 3 baterries in serial configuration, feed the UNO via the power jack and feed the neopixels with the 5V output pin.

I leave you a link to a video project I made, I used 60 LEDs and I power it with a 1A cell phone charger but I tested too with a 5V powerbank and works fine, in my case I made the prototype with an Arduino UNO and in the final product I use a Nano.

Robotech-e:
then you can feed the Arduino UNO via the power jack that way you can avoid disconnections

What does that mean? Makes no sense to me! :astonished:

Robotech-e:
you must remember that neopixels work at 5V then you will need to use a Step Down Converter to feed the LEDs

If you have a 5 V regulator, then you feed the Arduino with 5 V. Much more sensible. :sunglasses:

Robotech-e:
in my case I made the prototype with an Arduino UNO and in the final product I use a Nano.

UNOs are not practical for real world projects. Unless a "shield" provides all the necessary hardware. :grinning:

If you no longer need USB access, a Pro Mini is the most practical (and does not waste current).